If you have a bootable .dmg file containing a single compressed HFS+ partition image (e.g. MBR+1.hfs), then use 7Zip to extract the single partition image file (e.g. 1.hfs) and add it to your E2B USB drive (it can be renamed and given a .hfs or .hfsptn file extension). Example: Niresh Yosemite-Zone_10.10.1.dmg 4.96 GB (5,332,012,208 bytes) - extract 1.hfs.

Note: If you get a boot1:/boot error under VBox, try booting from a real system!

.dmg files that contain more than one partition are not currently supported.

You can create a USB Flash drive using Windows TransMac (right-click on USB drive - Restore with Disk Image) and then if it contains a HFS single partition, make a partition image .HFSptn file using RMPrepUSB - Disk->File - Start=P1, End=P1, FileStart=0). However, the .dmg image must be bootable and most Apple .dmg Installers/Upgrades are not bootable.

iPortable Snow x86 from E2B video with brief instructions in the Description here.

Note: When you run a .dmg or .hfs file, it creates a new partition entry #4. This partition entry is used by E2B and so is normally unused/empty.
E2B will complain about it when you reboot to the E2B drive and it will ask if you want to delete it (if you don't delete it then the E2B menu will not load!).

If you regularly use .dmg and/or .hfs files, you can add a 'partnew' command line to the \_ISO\MyE2B.cfg file to delete the #4 partition every time E2B boots. See the Sample_MyE2B.cfg file for more details.

MacOS High Sierra Installer

This process is untested as I do not have a Mac, but it seems to at least start to UEFI-boot!

Download the prepared clover.img and OSX_10.13.1_Installer.hfs from this article. I used the torrent download.

Install the MPI Tool Kit onto your Windows office system before you begin.

2. Copy the large .hfs file to the E2B USb drive (e.g. \_ISO\MAINMENU) - rename the file so it has no dots or file extension - e.g. OSX_10_13_1_Installer

3. Copy the OSX_10_13_1_Installer file to the same folder as the .imgPTN file

4. Run \MAKE_THIS_DRIVE_CONTIGUOUS (run as admin).cmd

5. Run \_ISO\SWITCH_E2B.exe and double-click on the OSX_10_13_1_Installer.imgPTN+OSX_10_13_1_Installer entry to switch it in.

6. Add this line to the large \menu.lst file on the E2B drive:

parttype (hd0,2) 0xAF

7. Now UEFI-boot on a Mac or Macintosh x86 system (must have correct CPU and >4GB RAM).

You can also try the Clover boot option (MBR-booting).

Other .hfs files can be substituted to install different versions.

If you regularly use .dmg and/or .hfs files, you can add a 'partnew' command line to the \_ISO\MyE2B.cfg file to delete the #4 partition every time E2B boots. See the Sample_MyE2B.cfg file for more details.